Mount Umunhum is one of the tallest peaks in the Santa Cruz Mountains, and has a rich history, first as a sacred site for Native Americans (“umunhum” means “resting place of the humming bird”), and more recently as a Cold War-era Air Force radar station. The radar station closed in 1980, and the land acquired for the Sierra Azul Open Space in 1986. The summit itself remained closed until fall of 2017, when remediation and clean-up work was mostly completed.
Distance: 7.7 miles
Time: 3 hours
Difficulty: Moderate
Elevation gain/loss: +/- 1,141′
Dogs: No
When to go: Year-round
Getting to the Trailhead
The trail begins at the Bald Mountain trailhead parking area in the Sierra Azul Open Space Preserve, about 40 minutes south of San Jose. Once you get on the narrow and crooked Hicks Road, you’ll follow it to Mt Umunhum Road and head uphill to the Bald Mountain parking area. There are parking spots for over 20 cars, and pit toilets and information signs with a map of the area, rules and regulations.
You can get turn-by-turn driving directions here on Google Maps. I drove down from Berkeley after rush hour on a Monday and my drive time was about 90 minutes.
Hiking to Mount Umunhum
Take a moment to check the latest park information at the information boards, then follow the crosswalk across Mt Umunhum Road to the trailhead.
The trail to the summit is 3.7 miles each way (7.4 miles or roughly 12 km round trip). I logged a bit more just wandering around the summit and learning more about the history from the info panels.  This trail is also part of the Bay Area Ridge Trail – an epic loop that’s on my to-hike list.
The forested trail was lush and green in January, with light rain keeping me cool and the clouds cloaking the trail in an ethereal mist. At about 0.4 miles, the trail reaches a junction with the Barlow Road trail – a double-track dirt road that descends down and connects with the Woods Trail. Follow the jog across Barlow Road and continue on the Mt Umunhum Trail as is climbs gradually up the north slope of Mount Umunhum.
The trail follows the contour of the mountain, crossing several watersheds via well-crafted footbridges. Walk quietly and you might be lucky enough to visit with some of the “locals” on the mountain.
Halfway to the summit there is a short spur to the Guadalupe Creek Overlook. It doesn’t add appreciable distance to the hike, though the view was obscured by the clouds.
With less than 1/4 mile to the summit, the view opens up a bit and the “cube” comes into view.
This cube is actually six-stories tall and was the base upon which the giant radar antenna stood. On a clear day, this landmark is visible from many parts of the South Bay. Unfortunately, that last segment of the trail is currently closed for further remediation and cleanup. You can still hike to the summit, following the detour that takes you over to the main summit parking area.
From here, you climb a series of steps to the summit.
Mount Umunhum Trail Map & Elevation Profile
Mount Umunhum Resources
- The summit is open from 7am to 30 minutes after sunset.
- There are no fees for entrance or parking, and there are no permits required.
- The parking is limited and can be crowded on weekends. If possible, go early or go on a weekday.
- Check the official Sierra Azul Open Space Preserve website for updates on current conditions, events, rules and regulations.
- Download the Sierra Azul Open Space Preserve Map (PDF).
- Mount Umunhum is part of the NorCal Six-Pack of Peaks Challenge, a great way to train for bigger adventures that supports Big City Mountaineers.
- Redwood Hikes has an overview of this trail with photos from a sunny day.
Mount Umunhum Weather Forecast
Originally hiked on January 22, 2018.
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